Lord Livius Erimond of Vyrantium is a magister of the Tevinter Imperium and an agent of the Venatori. He is a character in Dragon Age: Inquisition.
On behalf of Corypheus he manipulated Warden-Commander Clarel de Chanson by offering an alliance. He convienced her to sacriface Warden warriors by Warden mages to bind Demons, so they could become an army to invade Deep Roads and kill the Old Gods before they become archdemons. In fact that ritual binded the Warden mages to his master and he kept it in secret.
In the Western Approach Erimond is confronted by The Inquisitor while instructing Grey Warden mages in blood sacrifice. The Inquisitor can tell the mages that Erimond is only doing the sacrifice rituals to cause a Blight. Erimond will be shocked at the Inquisitor's accusation, but he and the mages won't accept it. He will tell the Inquisitor that Demons don't need food or rest, and that they will never disobey their masters or question orders. He will then say that the Warden mages did this on their own free will and that killing the Old Gods is the only solution. If Blackwall is present in the Party, he will become angry, calling Erimond's statement a lie, claiming that the Grey Wardens would never perform such tasks willingly. Likewise, if Solas is present, he will also become angry as well, warning Erimond that killing the Old Gods will more than likely only make things worse. Erimond's attempts to control the Inquisitor through magical manipulation of the Anchor backfire, leading him to flee to Adamant Fortress.
The Inquisitor then reports to the War Room, where the 3 advisors will explain that Adamant Fortress was built sometime before the Second Blight, meaning it was built before the age of modern siege equipment, which will allow them to do some major damage. Unfortunately, they will explain that a massive binding ritual will be present. They will believe that the warriors may be willing to listen to reason, but don't know if they'll turn on Erimond and Clarel directly. They do however, know that the mages are slaves to Corypheus, and will fight to the death. Luckily, several groups of Inquisition soldiers will be present in the assault and will assist as needed. The Inquisitor can then activate the Operation (Forces) for a price of 30 Power.
Erimond is pursued by the Inquisition, who lay siege to Adamant, but Erimond persuades Warden-Commander Clarel to initiate the summoning ritual. Clarel started to wonder when the Inquisitor told that Erimond is servant of Corypheus. If Blackwall is present in the Party, the Inquisitor can order him to speak to them, which he will say that the first time he put on the Warden armor, he felt like he was right where he belonged. (It will raise his approval rating as well.) Erimond summons Corypheus' dragon to kill the Inquisitor, but this backfires when Clarel mistakes it for an Archdemon and concludes (rightly) that Livius Erimond sees the Blight as a tool instead of as an enemy. If the Inquisitor successfully persuades them, the Warden soldiers will then attack the demons and assist the Inquisition. The mages however, won't be affected, regardless whether or not the persuasion was successful, and as a result, will immediately attack on sight.
Erimond is defeated by Clarel but escapes death after the Warden-Commander is devoured by the dragon. Despite the subsequent collapse of the rampart where he is situated, Erimond survives the Siege of Adamant and is brought back to Skyhold for judgement.
Chained Lord Erimond is dragged to face judgement for his crimes, though he refuses to recognize or accept the Inquisition's authority, claiming that death at their hands would be a validation, sending him to glory. As with all judgements, the Inquisitor can decide what punishment to give Erimond for his crimes.